Marine propulsion device with energy absorbing means



March 15, 1966 E. c. KIEKHAEFER 3,240,453

MARINE PROPULSION DEVICE WITH ENERGY ABSORBING MEANS Filed March 26,1964 2 Sheets-Sheet l i g i; W 2 2 r r E INVENTOR.

ELMER C. KIEKHAEFER Affomvsvs March 15, 1966 E. c. KIEKHAEFER 3,

MARINE PROPULSION DEVICE WITH ENERGY ABSORBING MEANS Filed March 26,1964 2 Sheets-Sheet 2 INVENTOR.

ELMER C. KIEKHAEFER vndrus Starkg Arromvevs 'downward portions of tiltof the device.

United States Patent Office 3,240,453 Patented Mar. 15, 1966 3,240,453MARINE PROPULSION DEVICE WITH ENERGY ABSORBING MEANS Elmer CarlKiekhaefer, Winter Haven, Fla., assignor to Kiekhaefer Corporation, Fonddu Lac, Wis.,ya corporation of Delaware Filed Mar. 26, 1964, Ser. No.354,860 8 Claims. (Cl. 248-4) This invention relates to a marinepropulsion device, and more particularly to a stern-mounted outboarddrive for boats.

Such drives may include, for example, the well-known outboard motor aswell as the more recently popular stern drive units connected to aninboard-mounted engine.

In all such devices, striking of an underwater object by the propelleror lower housing puts severe strain on the device itself as well as onthe transom of the boat to which the device is secured rearwardlythereof. If the impact is severe enough, and if the device is permittedto pivot freely about its horizontal tilt axis, undesirable slamming ofthe device may occur at the top and bottom ends of pivot travel.

Various means have been developed for restricting the freedom to tilt.One such means is disclosed in the present inventors US. Patent No.2,953,335, entitled Outboard Propulsion Units for Boats and assigned toa common assignee.

The present invention is directed to another form of clamping device andwhich is simple to construct and yet efficient and flexible inoperation. Generally, in accordance with the invention, an arcuate rackor gear sector is secured to the swivel bracket of the device andengages a pinion mounted on the clamp bracket. Vertical pivoting of theswivel bracket about the tilt pin causes the rack to drive the pinion. Aclutch connected to the pinion acts as an energy absorber to keeppivoting of the device under control.

Further in accordance with the invention, the arrangement is such thatthe rotatable clutch parts rotate a substantial multiple of the rotationof the device about the tilt pin. In addition, the construction of therack is such that the clutch operates only during selected upward andAdditionally, the gears are arranged to prevent transmission to thetransom of the initial impact load.

The accompanying drawings illustrate the best mode presentlycontemplated by the inventor for carrying out the invention.

In the drawings:

FIGURE 1 is a side elevation of a transom-mounted outboard motorembodying the invention, with the transom in section;

FIG. 2 is a section taken on line 2-2 of FIGURE 1;

FIG. 3 is an enlarged fragmentary side elevation showing the outboardmotor in normal running position;

FIG. 4 is a view similar to FIG. 3 with the motor in partially tiltedposition; and

FIG. 5 is a view similar to FIGS. 3 and 4 and with the motor in a higherposition of tilt.

As best shown in FIGURE 1 of the drawings, the concept of the inventionmay be applied to an outboard .motor 1 which comprises a power head 2, adrive shaft housing 3 extending downwardly from the head, and a lowergear housing 4 which carries a propeller 5. Housings 3 and 4 enclose theusual connections for driving propeller 5 from head 2, and with the headcomprise the power unit.

-Motor 1 is adapted to be secured to the transom 6 of a boat andrearwardly thereof. For this purpose, housing 3 is pendantly anddirigibly supported from the transom by a swivel bracket 7 whichsupports the motor on a generally vertically extending swivel pin 8whereby the motor is adapted for horizontal pivotal steering movement.The upper portion of swivel bracket 7 extends forwardly through aportion often referred to as the tilt bracket 9 which in turn ispivotally mounted for vertical tilting upon a transverse horizontal tiltpin 10 carried by a pair of clamp brackets 11. The arms of brackets 11are mounted to transom 6 by suitable manually operable clamping screws12.

Clamp brackets 11 are provided with a rearwardly projecting arm 13having spaced openings therein adapted to receive a tilt adjustment pin14 for selectively positioning motor 1 at a desired operating positionwith respect to the vertical.

During operation of an outboard motor-powered boat, propeller 5 mayoccasionally engage an underwater obstacle, such as a submerged log orthe like. As the boat continues forwardly, the motor and swivel bracket7 will tilt vertically about tilt pin 10. In view of todays increasedboating speeds, it is advisable to control the impact and tilt forces toreduce the hazard to both motor and boat. For this purpose, means areprovided to dampen or absorb the energy created by engagement of themotor with the obstacle.

In accordance with the invention, an arcuate rack or gear sector 15 issecured to the lower portion of each side of swivel bracket 7, as bybolts 16, and extend forwardly and downwardly therefrom. In the normaloperating position of the motor, the forward end portion of each gearsector 15 terminates closely adjacent tram-- som 6 (FIG. 3). Sectors 15are provided with a plurality of teeth 17 which are adapted to mesh witha plurality of corresponding teeth 18 on a corresponding pinion 19 whichis coplanar with the sector. Pinion 19 is keyed or otherwise fixed tothe end of a vertically and horizontally fixed rotatable clutch shaft 20disposed ad jacent gear sector 15. The axis of shaft 20 is parallel toand spaced downwardly and rearwardly from the axis of tilt pin 10. Theends of shaft 20 to which pinions 19 are affixed extend outside the arms13 of clamp brackets 11, and the shaft extends between the arms and issuitably journalled therein.

As shown in FIG. 2, shaft 20 carries a plurality of axially spacedclutch plates 21 between the clamp bracket arms, which plates in turnconstantly engage a plurality of corresponding clutch rings 22 carriedon the circumferential inner wall of a cylindrical clutch housing 23secured to one of the clamp bracket arms. Plates 21 are biased intoengagement with rings 22 by a suitable spring 24 extending between oneclamp bracket arm 13 and the closest adjacent plate. Spring 24 should beof a size and strength commensurate with the inventive concept, anddifferent size and strength springs may be utilized depending upon theweight of the outboard motor. It may be possible to relocate the clutchmechanism relative to clamp brackets 11 without departing from thespirit of the invention.

FIGS. 3-5 illustrate the action of the structure of the invention when amotor 1 strikes a submerged object.

FIG. 3 shows the device just a moment prior to impact with the object.In this position, teeth 18 of pinions 19 are not engaged with gearsector teeth 17 due to the fact that pinions 19 are adjacent portions ofsectors 15 having an untoothed area wherein an elongated bottom land 25extends inwardly or rearwardly from the innermost tooth. Land 25 is ofapproximately the same depth as the bottom lands between adjacent teeth17.

At the moment of impact, very large forces are applied to motor 1 whichcause it to tilt upwardly on tilt pin 10. Land 25 permits substantiallyfree upward initial tilt to thereby prevent transmission to the transomof the high initial impact force. Once this force is substantiallydissipated and upward tilting continues, gear sector teeth 17 engagepinion teeth 18"and pinions 19 are then rotated to actuate the clutch.to absorb the kinetic energy created. See FIG. 4.

Upon further upward tilting, and once the shock forces are substantiallyunder control, the resistance created by the clutch is no longer needed.Thus, as shown in FIG. 5, the outer or forward end of gear sectors 15run off pinions 19 to permit substantially free tilting at the uppermostposition.

The return tilt is approximately the reverse of upward tilt. Initialdownward tilting is free until the end teeth of sectors 15 engagepinions 19. Further downward tilting is controlled in accordance withthe clutch action, and final downward return is free. The amount of freefinal tilt will not produce sufiicientforce to cause damage toadjustment pin 14. This can be controlled by controlling the length ofbottom lands 25.

The amount of resistance afforded by the clutch mechanism must besufiicient to absorb substantial kinetic energy, but must below enoughtopermit return of the motor to running position without tending to holdthe tilt pin 10. Thus, if the maximum pinion radius is one inch andthe'distance between axes is :twelve inches: for every 30 of motor tilt,shaft 20 and its clutch plates 21 will rotate 360. v The inventionprovides a novel structural concept for con-trolling the destructiveforces released when an outboard mounted marine propulsion unit strikesa sub- I merged object. These forces are absorbed and dissipated, as byheat in the clutch, during the intermediate portion of tilt action. Inaddition, high absorbtive efiiciency is possible with a clutch ofrelatively small size, due to the .large angle of clutch rotation perdegree-ofmotor tilt.

Various modes of carrying out the invention are contemplated'asbeingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

1 claim:

1. In combination:

(a') an outboard propulsion device for boats,

(b) means for mounting said device rearwardly of the transom of a boat,

(c) means pivotally mounting said device on said mounting means and on ahorizontal tilt axis for tilt movement rearwardly and upwardly from anormal operative position,

(d) an arcuate teeth-carrying rack secured to said device and extendingdownwardly and forwardly therefrom,

(e) a pinion disposed co-planar with said rack and having teeth adaptedto be engaged by .said rack teeth,

(f) a rotatable shaft disposed adjacent said rack and fixed againsttilting with said device and having an axis spaced from and parallel tosaid tilt axis,

(g) said pinion being disposed for rotation with said shaft, a l

(h) and clutch means connected to said shaft for absorbing a substantialportion of kinetic energy,

(i) .the construction being such that striking of an underwater objectby said propulsion device causes said device to tilt upwardly about saidtilt axis so 'that said rack teeth engage. said pinion teeth to ur'otate said shaft and actuate said clutch means. 2. The combinationofclaim 1 in which: the distance between said tilt axis and saidshaftaxis is substantially The amount of the multiple 4. more than themaximum radius of said pinion so that every angle of tilt of said deviceis accompanied by a substantially greater angle of rotation of saidclutch shaft.

3. The combination of claim 1 in which:

(a) said rack includes an elongated bottom land extending rearwardlyfrom one of the rack teeth and of approximately the same depth as thebottom lands between adjacent rack teeth,

(b) said pinion being positioned adjacent said elongated land and out ofengagement with the rack teeth when said device is in normal operatingposition to permit substantially free and uncontrolled tilting of saiddevice at initial impact with a submerged object, followed bycoengagement of the rack and pinion teeth upon further upward tilting toactuate said clutch means.

4. The combination of claim 1 wherein: said rack is of such a lengththat the forward end thereof runs off said pinion adjacent the uppertilt position of the device to permit substantially free upward tiltingthereafter.

5. The combination of claim 3 wherein: said rack is of such a lengththat the forward end thereof runs off said pinion adjacent the uppertilt position of the device to permit substantially free upward tiltingthereafter.

6. The combination of claim 1 in which: the resistance to tiltingoffered by said clutch means is insuificient to prevent downward returnmovement of said device.

7. In combination:

(a) an outboard propulsion device for boats,

(b) means for mounting said device rearwardly of the transom of a boat,(c) means pivotally mounting said device on said mounting means and on ahorizontal tilt axis for tilt movement rearwardly and upwardly from anormal operative position, v (d) an arcuate teeth-carrying rack securedto said device and extending downwardly and. forwardly therefrom,

(e) a pinion disposed co-planar with said rack and having teeth adaptedto be engaged by .said rack teeth,

(f) a rotatable shaft disposed adjacent said rack and fixed againsttilting with said device and having an axis spaced from and parallel tosaid tilt axis,

(g) said pinion being disposed for rotation with said shaft,

(h) and constantly engaged clutch means connected to said shaft forabsorbing a substantial portion of kinetic energy,

(i) the construction being such .that striking of an underwater objectby said propulsion device causes said device to tilt upwardly about saidtilt axis so that said rack teeth engage said pinion teeth to rotatesaid shaft and actuate said clutch means,

(j) the distance between said tilt axis and said shaft axis beingsubstantially more than the maximum radius of said pinion so that everyangle of tilt of said device is accompanied by a substantially greaterangle of rotation of said clutch shaft,

(k) said rack including an elongated bottom land extending rearwardlyfrom one'of the rack teeth and of approximately the same depth as thebottom lands between adjacent rack teeth,

(1) said pinion being positioned adjacent said elongated land and out ofengagement with the rack teeth when said device is in normal operatingposition to permit substantially free and uncontrolled tilting of saiddevice at initial impact with a submerged object, followed bycoengagement of the rack and pinion teeth upon further upward tilting toactuate said clutch means,

(m) said rack being of such a length that the forward end thereof runsoff said pinion adjacent the upper tilt position to permit substantiallyfree upward tilting thereafter.

8. 'In combination:

(a) an outboard propulsion device for boats,

(b) means for mounting said device rearwardly of the transom of a boat,

(c) means pivotally mounting said device on said mounting means and on ahorizontal tilt axis for tilt movement rearwardly and upwardly from anormal operative position,

(d) an arcuate teeth-carrying rack secured to said device and extendingdownwardly and forwardly therefrom,

(e) a pinion disposed co-planar with said rack and having teeth adaptedto be engaged by said rack teeth,

(f) a rotatable shaft disposed adjacent said rack and fixed againsttilting with said device and having an axis spaced from and parallel tosaid tilt axis,

(g) said pinion being disposed for rotation with said shaft,

(h) and constantly engaged clutch means connected to said shaft forabsorbing a substantial portion of kinetic energy.

(i) the construction being such that striking of an underwater object bysaid propulsion device causes said device to tilt upwardly about saidtilt axis so that said rack teeth engage said pinion teeth to rotatesaid shaft and actuate said clutch means,

(j) the distance between said tilt axis and said shaft axis beingsubstantially more than the maximum radius of said pinion so that everyangle of tilt of said device is accompanied by a substantially greaterangle of rotation of said clutch shaft,

(k) said rack including an elongated bottom land extending rearwardlyfrom one of said rack teeth and of approximately the same depth as thebottom lands between adjacent rack teeth,

(1) said pinion being positioned adjacent said land and out ofengagement with the rack teeth when said device is in normal operatingposition to permit substantially free and uncontrolled tilting of saiddevice at initial impact with a submerged object, followed bycoengagement of the rack and pinion teeth upon further upward tilting toactuate said clutch means,

(m) said rack being of such a length that the forward end thereof runs01f said pinion adjacent the upper tilt position to permit substantiallyfree upward tiltin g thereafter,

(n) the resistance to tilting offered by said clutch means beinginsufiicient to prevent downward return movement of said device.

References Cited by the Examiner UNITED STATES PATENTS CLAUDE A. LE ROY,Primary Examiner.

1. IN COMBINATION: (A) AN OUTBOARD PROPULSION DEVICE FOR BOATS, (B)MEANS FOR MOUNTING SAID DEVICE REARWARDLY OF THE TRANSOM OF A BOAT, (C)MEANS PIVOTALLY MOUNTED SAID DEVICE ON SAID MOUNTING MEANS AND ON AHORIZONTAL TILT AXIS FOR TILT MOVEMENT REARWARDLY AND UPWARDLY FROM ANORMAL OPERATIVE POSITION, (D) AN ARCUATE TEETH-CARRYING RACK SECURED TOSAID DEVICE AND EXTENDING DOWNWARDLY AND FORWARDLY THEREFROM, (E) PINIONDISPOSED CO-PLANAR WITH SAID RACK AND HAVING TEETH ADAPTED TO BE ENGAGEDBY SAID RACK TEETH, (F) A ROTATABLE SHAFT DISPOSED ADJACENT SAID RACKAND FIXED AGAINST TILTING WITH SAID DEVICE AND HAVING AN AXIS SPACEDFROM AND PARALLEL TO SAID TILT AXIS, (G) SAID PINION BEING DISPOSED FORROTATION WITH SAID SHAFT, (H) AND CLUTCH MEANS CONNECTED TO SAID SHAFTFOR ABSORBING A SUBSTANTIAL PORTION OF KINETIC ENERGY, (I) THECONSTRUCTION BEING SUCH THAT STRIKING OF AN UNDERWATER OBJECT BY SAIDPROPULSION DEVICE CAUSES SAID DEVICE TO TILT UPWARDLY ABOUT SAID TILTAXIS SO THAT SAID RACK TEETH ENGAGE SAID PINION TEETH TO ROTATE SAIDSHAFT AND ACTUATE SAID CLUTCH MEANS.